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Further Investigation of Environmental Kuznets Curve Studies Using Meta-Analysis

Bishwa S. Koirala, Hui Li, Robert P. Berrens


With continued growth in available evidence, statistical investigation of the systematic variation across environmental Kuznets curve (EKC) studies may improve understanding of the relationship between economic growth and environmental quality. This investigation uses meta-analysis, based on 878 observations from 103 empirical EKC studies (1992 to 2009), to explore this relationship. Relative to earlier meta-analyses, this meta-analysis has larger data set (49% more observations), and includes a broad dis-aggregation across environmental degradation measures (according to physical and chemical properties). Using cluster analysis to account for heterogeneity across studies, econometric results indicate that the type of environmental quality indicator significantly affects the presence of an EKC relationship, and any predicted income turning points (ITPs). Results indicate the presence of an EKC-type relationship for landscape degradation, water pollution, agricultural wastes, municipal-related wastes and several air pollution measures. However, in the high-profile case of CO2, the predicted value of the corresponding ITP is both extremely large in relative terms (about 10 times the world GDP per capita in 2007 purchasing power parity), far outside the observed range of the data, and significantly above any income growth scenarios (e.g., IPCC, 2000) for the 21st century that control CO2 to acceptable levels (e.g., 354 ppm in 1990). Thus, the EKC literature offers no basis for predicting that continued economic growth will lead to significantly reduced CO2 emissions, absent specific policy actions to do so.


Environmental Kuznets Curve, Income Turning Points, Meta-Analysis

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